Now, this is realy extremly strange. I went to work this morning. So I wanted to know, how much battery the Nook will use, while he has Wifi turned on. Now, see the suprising result:

Airplane mode: on
Wifi: on
Battery: 74%
Sleep modus

I started this test at 8:45 and ended it at 13:45 so he was exactly for 5 hours asleep. When I woke him up and looked at the battery status it said 73%. Which would mean in 5 hours with wifi on and airplane mode on it used only 1%!!! Which would mean, it uses less than with wifi turned off. That is strange.

I start to think that maybe the 3G network is causing this problem. Over here in Germany I cannot connetc to the AT&T network and I never saw the network sign in the upper corner on my Nook. I know with my iPHone it was the same problem in the beginning. It used a lot of battery power trying to connect all the time to a network. So as long as you stay in the same wifi network the Nook is not busy trying to connect you to a different network. That is at least the only explanation I have for this.

I really don't think you can trust the battery meter at the level of precision you're asking for. The charge level will change with temperature, for example; it will have a higher charge when it's warmer than when it's cooler. It's OK when it comes to knowing whether it's fully charged, half charged, or almost empty, but you can't really trust it more than that.

it. it. IT!
Not "him".
It's one thing to know how long you can keep a reader in your drawer and it will still turn on. It's another to read on it (nudge, nudge, "it") for an extended period of time. I think even the frequency of your page-turning will have an influence on the battery life.

The problem with airplane mode is that they are often not well tested (they usually do turn off the wireless, but they often have side effects). I would not be surprised if this mode drained the battery. The only way to confirm is to repeat the test, perhaps for a longer period, with a fully charged battery and have others try the same test.

On my old Nokia 770, I don't think WiFi had much effect on battery life even when it was not present. This is because it was only turned on when I asked for internet access, and was automatically (and aggressively) turned off when not in use. So airplane mode with WiFi on may not be a bad default setting, except on an airplane.

My nook is a "she". I call her Mona. Don't ask. I'm wondering if anyone have made any empirical comparisons between 1.1.1 and 1.2 as many people have commented on a marked improvement on battery life after updating to 1.2.